Tuesday, September 30, 2014

This is just a fun record of an interesting prey item for a very pretty sea anemone. Eric and I have continued our surveys of Bull Kelp holdfasts. Recently, we found this beautiful Moonglow Anemone (Anthopleura artemisia) in a holdfast. When we looked at it underwater, Eric noticed that it was holding on to some unusual food items!

It's important to remember that these holdfasts can be drifting around offshore for a while, so they can be substrate for pelagic species.

This Moonglow Anemone was eating cyprids (the final larval stage) of pelagic gooseneck barnacles (Lepas spp.). It's probably an unusual food item for a Moonglow Anemone, as more often these anemones live on the bottom in intertidal or subtidal habitats where they're not likely to encounter pelagic barnacles.

Below is a closeup of the barnacle cyprids. (If you'd like to see better pictures and learn more about this type of cyprid, review the post from 2 July 2012.)

And here's one more picture: A closeup of the anemone's tentacles. I'm guessing every tentacle has a different pattern!

Monday, September 29, 2014

House Wren (Troglodytes aedon), photographed on Bodega Head on 14 September 2014

I loved the subtle barring on the wings. The Birds of North America account said the coloration of the upperparts could be described as brown, cinnamon olive brown, or "Prout's brown." I wasn't sure what Prout's brown was, but eventually located a definition that said it was a dark olive brown. Which do you think is the best match?

Sunday, September 28, 2014

This remarkable animal is a sea butterfly, Hyalocylis striata. Kate and Emily discovered it when sorting the contents of a deep-water plankton tow from >200 meters depth during an ACCESS (Applied California Current Ecosystem Studies) cruise over Bodega Canyon on 24 September 2014.

A sea butterfly is a type of pelagic snail called a pteropod. It spends its entire life at sea. Note several special adaptations, highlighted in the photo above and the diagram below.

The foot has been modified into two, large wings for swimming. The wings flap together, and slowly, hence the name sea butterfly.

The shell is transparent, and very thin and fragile, traits associated with an open ocean existence.

Modified from Invertebrates (Second edition) by Brusca and Brusca (2003)

Although other pteropods have been documented in this area, Hyalocylis striata is unusual. Typically it is a warm-water species; most records appear to be tropical and subtropical. We're actually trying to figure out if this might be the first definite record for California.

I've done a very basic literature search, as well as a search of online museum collections. So far I can't find any records along the West Coast north of Baja California, Mexico. In 1967, McGowan published a Distributional Atlas of Pelagic Molluscs in the California Current Region. The map below is the only cruise for which he reported finding Hyalocylis striata. Each dot on the map is a sampling station. Can you locate the station where Hyalocylis was found?

I'm guessing you found the one station off the west coast of Baja where Hyalocylis was discovered, just south of 25°N latitude.

This atlas, along with several other sources, makes it seem like Hyalocylis is generally not expected to be at 38°N, the latitude of Bodega Bay.

It may be that Hyalocylis is another species brought north with the warmer-than-usual water this summer. For example, warmer ocean temperatures near shore during the mid-late summer are usually in the range of 13-15°C (55-58°F); this summer they have been around 16-18°C (60-64°F). When I was near Bodega Canyon/Cordell Bank on 19 September, it was 19°C (66°F)!

Although these sea butterflies are small (up to 8 mm long), it's fun to imagine them flying over Bodega Canyon!

P.S. Many thanks to Roger Seapy for helpful discussions about Hyalocylis striata.

P.P.P.S. The Applied California Current Ecosystem Studies (ACCESS) Partnership is an ongoing collaboration between Point Blue Conservation Science, Cordell Bank and Gulf of the Farallones National Marine Sanctuaries, to support marine wildlife conservation and healthy ecosystems in northern and central California. For more information about ACCESS, visit www.accessoceans.org, and for new collaboration opportunities contact Jaime Jahncke at jjahncke@pointblue.org.

Thursday, September 25, 2014

I didn't mention that the heteropods have a larval stage that looks very different than the adult. And although I've talked about veligers (the larval stage of most marine snails) before, e.g., see post from 11 September 2014, this veliger is noticeably different.

Check out those lobes! Many veligers have a velum (a lobed, highly ciliated structure surrounding the head that is used for swimming and feeding), but it's unusual for the velum to have 6 lobes. When we saw this veliger, we knew it was something different right away, just because of the spectacular multi-lobed velum.

Note that the shell of the veliger is different than the shell of the adult. It's much more rounded (see below):

But just like the adult, the larva can withdraw completely (velum and all) inside the shell:

This veliger was discovered by Emily after a plankton tow off Bodega Head on 9 September 2014. Eric has kept it alive in the lab since then and we've seen it developing and growing.

Thiriot-Quiévreux (1973) provided a helpful table with three stages of development in an atlantid heteropod. As development proceeds, the shell, velum, eyes, and foot all become more complex (see below).

When we first looked at it, the veliger was in Stage II — two of the lobes were much smaller than the others, the eye spots were relatively small and rounded, and the foot wasn't that noticeable.

However, within 9 days, we saw dramatic changes as the veliger transitioned to Stage III. The smaller lobes grew substantially so that all 6 lobes on the velum are now of equal size. The eye spots have become more visible and are now teardrop-shaped. And the foot has grown as it develops into a swimming fin.

Below are two images so you can see the changes in the velum (the growth of the smaller lobes). And then you'll get to watch a video with the veliger in action!

Velum with two smaller lobes (they look like the thumbs on a pair of mittens):

Velum with all 6 lobes of equal size:

And here's the highlight video — it shows the atlantid heteropod veliger actively swimming. Watch for all of the things discussed above — the long cilia beating along the edges of the velum, the rounded shell, and the transition from having 2 smaller lobes to all 6 lobes of equal length. By the way, this veliger is less than 0.5 mm long, so we're thankful that a microscope video camera can provide such nice views of this tiny whirling wonder!

Wednesday, September 24, 2014

Don't worry if you're not familiar with this animal yet. They're microscopic, so not easily observed without special equipment. But they're fascinating, so I'm sure you'll want to learn more about them soon!

Thanks to Emily, we had our first chance to photograph and film an atlantid heteropod (Atlanta sp.) that was caught in a plankton tow off Bodega Head on 17 September 2014.

Heteropods
are pelagic snails. They spend their entire lives floating and
swimming in the open ocean. You can see several adaptations to a
planktonic existence — a
mostly transparent body and shell, a foot that's been modified into a
swimming fin, large eyes, and a radula (basically a tongue) with sharp teeth for grasping and tearing prey. Heteropods are active,
visual predators. [Facts from Roger Seapy's excellent introduction to heteropods on the Tree of Life web page.]

Here's the video. [This is pretty special, as we can't seem to locate many heteropod videos on the Internet.]

The diagram below illustrates the main body parts visible in these pictures and the video.

Modified from The Light and Smith Manual (2007)

Note the coiled shell with the unusual keel that extends from the edge of the outermost whorl. The keel apparently helps stabilize the animal as it swims with back-and-forth undulations of the swimming fin.

The animal can withdraw completely into its shell. When it does, it can close the aperture (opening) of the shell with its operculum, just like many intertidal snails that you're probably familiar with.

The fin sucker is used to secure prey, e.g., other pelagic gastropods.

The proboscis is extensible, like an elephant's trunk. It's transparent, so you can see the radula inside — the radula looks a bit like a small zipper.

The eyes are large and dramatic. Atlantid heteropods are known for interesting eye-scanning movements, which you saw in the video. Look for the rounded lens (it looks silvery). It's thought that the eyes can pick up reflected light off stationary objects.

Here's another picture to look for all of these structures:

This heteropod was swimming, so it was difficult to photograph. Below, look for the keel at the lower edge of the shell. The gill is also visible inside the largest shell whorl.

Although many atlantid heteropods are pictured as I've shown them in the first two images, their normal swimming position is with the swimming fin held up towards the surface. So it's helpful to think about them like this:

P.S. If you need an explanation of the video: There are a few different things going on. It starts with an overview of the entire animal. The eye-scanning behavior will be obvious. A close-up reveals the radula moving inside the proboscis. Then you'll see the gill and a close-up of the heart pumping. (Amazing!) After that, the heteropod extends its proboscis and its tentacles, then swims away. The video ends with a few more images to help you appreciate this little-known animal.

P.P.S. Most atlantid heteropods are found in tropical and subtropical latitudes. One species, Atlanta californiensis, is found along the West Coast up to British Columbia. The Light and Smith Manual (2007) says that Atlanta californiensis is abundant is southern California, but we're not certain how common it is in northern California. We're trying to get help identifying this individual to find out which species it is.

Tuesday, September 23, 2014

I hope you'll forgive me (can you see me winking?), but I'm going to revisit the Blue Buoy Barnacles (Dosima fascicularis). A number of questions and discoveries came up after the original post on 31 August, and you never know when you will see them again, so it seems worth highlighting a few more things.

"Who are the hitchhikers?"

Some people noticed smaller barnacles attached to the Blue Buoy Barnacles. This is another species of pelagic barnacle called Lepas anatifera. Look closely (photo above and below), and you'll notice a few differences between the two species:

The Blue Buoy Barnacles make their own float, while Lepas doesn't. The Blue Buoy Barnacles are "blue," while Lepas isn't. The plates of the Blue Buoy Barnacles are barely visible and are basically transparent (more about that soon), while the plates of Lepas are opaque white. And another visible difference is the cirri (the appendages that the barnacle spreads like a fan to capture food). Blue Buoy Barnacles have robust cirri with substantial bristles. Lepas has longer, more slender cirri with finer bristles. (This means they catch different types of prey!)

Here's a close-up view of Lepas (growing on Blue Buoy Barnacles) taken under the microscope:

It's hard not to wonder if all of these hitchhiking Lepas will weigh down the buoy as they grow larger?

"Are they calcified or not?"

Some people asked about the plates of the Blue Buoy Barnacles and whether they are calcified or not. Of the five plates present, three of them are visible from one side (see labeled picture below):

Some of the Blue Buoy Barnacles that we found washed up on the beach weren't alive, so we were able to look at their plates in more detail. Here's a scan of one scutum and one carina.

These plates were incredibly fragile— I had to pick them up with a fine paintbrush. I would agree with the description in Morris, Abbott, and Haderlie, i.e., that Blue Buoy Barnacles have "thin, papery calcareous plates." I also found one other source that stated they were "almost uncalcified" (Cheng and Lewin 1976).

"Fiona!"

I can't help it...this is just too interesting not to share. While scanning the Lepas for any signs of juvenile Blue Buoy Barnacles, I came upon two tiny juvenile Fiona pinnata feeding on the Lepas! I wrote about the nudibranch Fiona last night and mentioned that when they feed on Velella they're blue, but when they feed on barnacles, they're brown. Well, here are two examples of very small brown Fiona on Lepas on Dosima!

"A question about the float"

During one scan of the Blue Buoy Barnacle floats, I was surprised to see a lot of little eyes looking up at me!

A closer view revealed that they were small barnacle cyprids (the settling stage of barnacle larvae). At first I thought perhaps they could be Blue Buoy Barnacle cyprids, but then I realized that there were a lot of them, and they were all on their sides, which isn't the normal position. Puzzling over this, my best guess right now is that these cyprids got stuck in a new layer of float cement that the barnacle had secreted — it's apparently very sticky before it hardens. Was this an accident? Or does the sticky cement also act as a defense so that animals don't start to live and grow on the barnacle's float?

"And finally, a video!

I saved the best for last, so I hope you're still with me. Although I hadn't revealed it yet, Eric filmed these barnacles to have a record of them for Bodega Head and to document their behavior. It's an unusual opportunity to see a beautiful pelagic barnacle in action. He filmed them in a small aquarium and under a microscope and then set it to music — click on the link below and enjoy!

The extreme close-up above might be a little puzzling at first. I'll zoom out a little more, and then I'll show some pictures of the entire animal.

Okay, here we go, the next two photos will give it away.

This is Fiona pinnata, a pelagic nudibranch. I first wrote about Fiona on 19 October 2012, but in that case those individuals were brown. Fiona's color depends on its food. When eating barnacles, they're brown, but when eating By-the-wind Sailors, they're intensely blue! This is the first time we've seen the blue form of Fiona pinnata.

Eric's sharp eyes first spotted Fiona's egg capsules on Velella sails washed up on the beach. Then I found one Velella with both eggs and a nudibranch! We started looking for others, and counted at least 20 Velella sails with Fiona egg cases and at least 12 blue nudibranchs!

Below are two examples of what they looked like on the beach (the off-white blobs are the egg masses):

We weren't sure what kind of condition they'd be in after a journey through the surf zone, but to document their occurrence in Bodega Bay this year, we brought a few back to the lab for photographs. The next image was taken in a small aquarium:

The whorled egg masses are packed with developing embryos:

When the nudibranchs turned on their sides, you could see what looked like developing eggs inside:

If you're wondering about the blue color...well, so am I. I watched Fiona actively feeding on Velella. Fiona's digestive tract extends into its cerata (the structures on its back). So the reason you're seeing blue is because you're seeing fragments of ingested Velella.Benjamin Kropp wrote about this after an experiment in 1931. When he starved or fed blue Fiona different food, they lost their blue coloration within 2-3 days. When he fed them Velella again, they regained their blue coloration within 2-4 hours![See Kropp, B. 1931. The pigment of Velella spirans and Fiona marina. Biol. Bull. 60: 120-123.]

It's officially fall now (when I'm writing this), but I can't help wonder if another blue animal will be discovered before the water turns cold again?

Sunday, September 21, 2014

During late summer and fall, I try to get out on at least one or two pelagic trips to Bodega Canyon and Cordell Bank. I went out on September 19th with Shearwater Journeys aboard the New Sea Angler. Here are a few trip highlights:

Guadalupe Murrelet (Synthliboramphus hypoleucus)— (in 2012, Xantus's Murrelet was split into two different species, Scripps's Murrelet and Guadalupe Murrelet). Guadalupe Murrelet is one of the southernmost breeding alcids (a group that includes auks, auklets, guillemots, murres, murrelets, and puffins). They nest on islands off the west coast of Baja California and then disperse northward after the breeding season. However, it's rare to see them in central/northern California.

Note the amount of white on the face and how it arches up and over the eye. Also look for the white wing linings in the last picture (below).

We also had great looks at an adult Tufted Puffin (in non-breeding plumage):

And although challenging to photograph, there was a good number of Arctic Terns (Sterna paradisaea), ~180 during the entire trip.

This Orca wasn't rising very far above the surface, but here's another image in case it's useful for identification purposes:

Every trip out to sea is different, and I'm thankful for every opportunity to become more aware of our "offshore neighbors." Spending time on a boat changes how I look at the ocean from land. When I scan the western horizon from Bodega Head, I visualize these amazing animals and wonder about their lives in the open ocean. It's helpful and inspiring to know who lives out there!